Radio Frequency Identification (RFID) technology is becoming widely used to identify and control the flow of goods, for instance, to identify packages, pallets and parcels, or RFID tags or tickets or labels (hereafter the term “tag” also covers tickets or labels) are used in conjunction with security-locks in cars and for access control in buildings. Heretofore, RFID tags have been applied to goods in various ways. They may be glued to the article surface, taped, or otherwise merged into the product itself. A variety of substrate materials are used to produce such tags and an economic way to produce the tags is to manufacture them in a web format making use of large quantity roll-to-roll type manufacturing methods.
It is necessary to roll such webs in order to store and transport them in an effective manner. In a tightly packaged roll having a web with tags comprising antennas and microelectronic chips, the chips (with certain height) in the web roll tend to become stacked on top of each other in consecutive rounds of the roll. This causes mechanical stress on the chips and results in breaking of the chips, and as a consequence, neither the chip nor the antenna works properly.
The problem can be solved, for example, by overlaminating the tags where a microelectronic chip is placed in a specific cavity so that the structure has a more constant thickness. However, this is, of course, an expensive way to solve the problem.
One solution to this problem is disclosed in the publication US2007181726A by Ishikawa et al, where a series of RFID tags is rolled around a reel core formed by a core material, and a stress absorbing material is wrapped around the core material to absorb the stress produced in reeling the series of RFID tags. Therefore, defects such as breaking of the antenna or damaging of the chip can be avoided to a greater extent. This kind of a solution, however, needs more production material and space when storing or transporting these rolls.
There is a need for a method which produces rollable webs in which the microelectronic chips could remain undamaged during storage and transport.